Worksheet 6 Wrap Up

Which of the following channels may be involved with a change of potential more negative than the value of resting membrane potential (hyperpolarized)? Choose all that apply,

Chemically gated K+ channels Voltage gated K+ channels During a graded potential, if chemical-gated K+ channels open K+ diffuses out of the cell, the potential become more negative (below resting membrane potential) and the cell is inhibited. During an action potential, voltage-gated K+ channels during the second half of the action potential. These channel stay open longer than Na+ voltage-gated channels, resulting in a hyperpolarizing stage during the action potential.

Which of the following channels are associated with the repolarization phase of an action potential?

K+ voltage gated channel

Which of the following channels are associated with the depolarization phase of an action potential?

Na+ voltage gated channel

Which of the following protein channels are NOT directly involved in graded (local) potentials?

Voltage gated channels; "open" when the potential across the membrane (the gradient of ions) changes from RMP to a threshold value (usually -55mv). This occurs after an excitatory graded potential at the cell body/dendrites has occurred.

Na+/K+ pumps functions during the duration of an action potential.

true

An action potential will continue to "boost" itself down the entire axon of a neuron; therefore after an action potential is initiated it is irreversible and will result in communication to the next neuron or target tissue of the circuit.

true; Action potentials are always irreversible compared to graded potentials. "Failed" graded potentials (those that do not reach threshold will reverse back to resting membrane potential because of the pumps.

Activation (opening) of K+ chemically or mechanically gated channels during a graded potential will lead to an action potential.

true; K+ channels with inhabitation of neurons